Abstract：
Recessive genic male sterility (RGMS) provides an effective approach for the commercial exploitation of heterosis, especially in Brassica crops. Although some artificial RGMS mutants have been reported in B. rapa, no causal genes derived from these natural mutants have been identified so far. In this study, a spontaneous RGMS mutant Bcajh97-01A derived from the \'Aijiaohuang\' line traced back to the 1980 s was identified. Genetic analysis revealed that the RGMS trait was controlled by a single locus in the Bcajh97-01A/B system. Bulk segregant analysis (BSA) in combination with linkage analysis was employed to delimit the causal gene to an approximate 129 kb interval on chromosome A02. The integrated information of transcriptional levels and the predicted genes in the target region indicated that the Brmmd1 (BraA02g017420) encoding a PHD-containing nuclear protein was the most likely candidate gene. A 374 bp miniature inverted-repeat transposable element (MITE) was inserted into the first exon to prematurely stop the Brmmd1 gene translation, thus blocking the normal expression of this gene at the tetrad stage in the Bcajh97-01A. Additionally, a co-segregating structure variation (SV) marker was developed to rapidly screen the RGMS progenies from Bcajh97-01A/B system. Our findings reveal that BraA02g017420 is the causal gene responsible for the RGMS trait. This study lays a foundation for marker-assisted selection and further molecular mechanism exploration of pollen development in B. rapa.
摘要：
隐性雄性不育(RGMS)为杂种优势的商业化开发提供了有效的途径,尤其是芸苔属作物。尽管在B.rapa中已经报道了一些人工RGMS突变体，到目前为止，还没有发现来自这些天然突变体的因果基因。在这项研究中,鉴定出一种自发的RGMS突变体Bcajh97-01A，该突变体源自可追溯到1980年代的“爱教黄”系。遗传分析表明，RGMS性状由Bcajh97-01A/B系统中的单个基因座控制。采用大量分离分析（BSA）与连锁分析相结合，将致病基因限定为A02染色体上大约129kb的间隔。靶区域中转录水平和预测基因的整合信息表明编码含PHD的核蛋白的Brmmd1(BraA02g017420)是最可能的候选基因。将一个374bp的微型反向重复转座元件（MITE）插入第一个外显子，以过早终止Brmmd1基因的翻译，从而在Bcajh97-01A中阻断该基因在四分体阶段的正常表达。此外,开发了一种共分离结构变异（SV）标记，以从Bcajh97-01A/B系统中快速筛选RGMS后代。我们的发现揭示BraA02g017420是负责RGMS性状的因果基因。本研究为基于标记的辅助选择和进一步探索水母花粉发育的分子机制奠定了基础。
